吸尘罩的优选及其在玉石雕刻防尘中的应用

目的对适用吸尘罩进行优选,并在实际通风除尘系统中应用。方法用示踪气体法对吸尘罩进行优选,比较不同吸尘罩捕集效率和风量的关系;对吸尘罩前风速分布进行测定,得出罩前风速分布模型。并对吸尘罩进行空气动力性能分析,测定雕刻排气中粉尘的粒径分级组成和除尘器的粉尘粒径分级除尘效率,评估除尘器的总除尘效率。结果优选出的雕刻吸尘罩,置于切割轮正前方0.11 m处,其控制风速为0.5 m/s,能有效地控制雕刻切割轮的粉尘不向周围扩散,工作地点空气粉尘浓度由无罩时的30-297 mg/m3降低至1.1-1.7 mg/m3,吸尘罩风量为255 m3/h,为其他类型吸尘罩的50%-77%。优选出的冲击水浴除尘器,其除尘效率为97%-98%,阻力为1.5 kPa;滤袋除尘器的效率为98%-99%,阻力为2.5 kPa;除尘后尾气的粉尘浓度为20-30 mg/m3。结论提出了优选吸尘罩的设计方法及实用的除尘器,可供实际应用。     

Nurses’ knowledge,experience and self-reported adherence to evidence-based guidelines for prevention of ventilator-associated events: A national online survey

ObjectiveTo explore Australian intensive care nurses’ knowledge of ventilator-associated pneumonia and self-reported adherence to evidence-based guidelines for the prevention of ventilator-associated events.DesignA quantitative cross-sectional online survey was used.SettingThe study was conducted in two Australia intensive care units, in large health services in Victoria and an Australia-wide nurses’ professional association (Australian College of Critical Care Nurses).Main outcome measuresParticipants’ knowledge and self-reported adherence to evidence-based guidelines.ResultsThe median knowledge score was 6/10 (IQR: 5–7). There was a significant positive association between completion of post graduate qualification and their overall knowledge score p = 0.014). However, there was no association (p = 0.674) between participants’ years of experience in intensive care nursing and their overall score. The median self-reported adherence was 8/10 (IQR: 6–8). The most adhered to procedures were performing oral care on mechanically ventilated patients (n = 259, 90.9%) and semi-fowlers positioning of the patient (n = 241, 84.6%). There was no relationship between participants’ knowledge and adherence to evidence-based guidelines (p = 0.144).ConclusionParticipants lack knowledge of evidence-based guidelines for the prevention of ventilator-associated pneumonia. Specific education on ventilator-associated events may improve awareness and guideline adherence.     

The role of pulmonary CO2 flow in the control of the phase i ventilatory response to exercise in humans

To gain an insight into the origin of the phase I ventilatory response to exercise (ph I) in humans, pulmonary ventilation WE) and end-tidal partial pressures of oxygen and carbon dioxide (P _ETO₂ and P _ETCO₂, respectively) were measured breath-by-breath in six male subjects during constant-intensity exercise on the cycle ergometer at 50, 100 and 150 W, with eupnoeic normocapnia (N) or hyperpnoeic hypocapnia (H) established prior to the exercise test. Cardiac output (Q₂) was also determined beat-by-beat by impedance cardiography on eight subjects during moderate exercise (50 W), and the C0₂ flow to the lungs (Q₂·C_vCO₂ where C_vCO₂ is concentration of CO₂ in mixed veneous blood) was estimated with a time resolution of one breathing cycle. In N, the initial abrupt increase of PE during ph I (V_E approximately 18 l · min^–1 above rest) was followed by a transient fall. When P _ETCO₂ started to increase (and P _ETO₂ decreased) V_E increased again (phase II ventilatory response, ph II). In H, during ph I V_E was similar to that of N. By contrast, during ph II V_E kept gradually decreasing and started to increase only when P _ETCO₂ had returned to approximately 40 mmHg (5.3 kPa). Thus, as a result of the prevailing initial conditions (N or H) a temporal shift of the time-course of V_E during ph II became apparent. No correlation was found between C0₂ flow to the lungs and V_E during ph I. These results are interpreted as suggesting that an increased C0₂ flow to the lungs does not constitute an important factor for the initial hyperventilatory response to exercise. They are rather compatible with a neural origin of ph I, and would support the neurohumoral theory of ventilatory control during exercise.     

Inhibition of HA Synthase 3 mRNA Expression, with a Phosphodiesterase 3 Inhibitor, Blocks Lung Injury in a Septic Ventilated Rat Model

Low-molecular-weight hyaluronan produced by hyaluronan synthase 3 (HAS3) has been shown to play a role in acute lung injury secondary to high-tidal-volume ventilation. Phosphodiesterase 3 inhibitors have been shown to decrease HAS3 expression. We hypothesized that low-molecular-weight hyaluronan (LMW HA) produced by HAS3 mediates LPS-induced lung injury in the mechanically ventilated rat and that milrinone (MIL), by blocking HAS3 mRNA expression, would prevent the injury. Rats were randomized to four groups: controls with mechanical ventilation at 7 cc/kg MV, MV+LPS, MV+MIL, and MV+LPS+MIL. Rats were intubated and ventilated without PEEP for 4 h. Lipopolysaccharide (LPS) (1 mg/kg) was infused into the arterial line 1 h prior to MV. MIL 10 μg/kg/min (or an equivalent volume of saline) was infused through the venous line at the beginning of MV. Bronchoalveolar lavage fluid (BAL) was collected after 4 h of ventilation and lungs were saved for histopathology. LPS significantly increased neutrophil infiltration and protein concentration in the BAL and augmented lung injury score on histology. MIL significantly lowered alveolar protein and neutrophil infiltration as well as lung injury in response to LPS. Furthermore, MIL decreased the mRNA expression for HAS3 and MIP2 in lung tissue and decreased the protein content in BAL. MIL, a commonly used inotropic agent, inhibited LPS-induced lung inflammation and lung injury in mechanically ventilated rats. The anti-inflammatory properties of MIL may be mediated by inhibition of HAS3 and/or MIP2 and could be beneficial in the treatment of sepsis.     

Intrapulmonary percussion ventilation: operation and settings

Intrapulmonary Percussion Ventilation (IPV) was designed to promote airway clearance, to recruit areas of lung and to improve pulmonary gas exchange. Its principle is to administer bursts of small tidal volume at high frequency. This article describes IPV devices, especially the Phasitron(?), which provides a dynamic interface between the pneumatic source of gas and the patient. Although not fully understood, the principles of action are also discussed. Finally, available settings of IPV are proposed following two strategies. In patients with obstructive respiratory disease and ventilatory autonomy, the vibrations and percussions are applied with a frequency more than 300?cycles/min and pressure in the proximal airways ranging from 10-20cm. H(2)O. In patients with restrictive pulmonary disease but without ventilatory autonomy, IPV is expected to improve gas exchange. The frequency of percussion will be slower (80-200?cycles/min) but the proximal airway pressure may reach 40cm H(2)O. During the sessions, the frequency may be modified to alternate from a percussive pattern (high frequencies promoting the mobilization of secretions) to a ventilatory pattern (slow frequencies encouraging alveolar ventilation and clearance of secretions).     

右美托咪定联合丙泊酚在ICU中的应用

目的:探讨α2-肾上腺素受体激动剂右美托咪定(dexmedetomidine)联合丙泊酚(propofol)用于重症监护室(ICU)中术后机械通气患者的镇静效果及安全性。方法:选择术后带气管导管进入ICU继续进行机械通气治疗的患者180例,随机分为3组,每组60例,组均给予芬太尼持续静脉泵入镇痛,剂量为0.30μg/(kg.h)。右美托咪定联合丙泊酚组(简称A组)先于10 min左右缓慢静注右美托咪定0.5μg/kg,然后改用微量注射泵持续静注右美托咪定,维持量为0.10-0.20μg/(kg.h),同时静脉持续泵入丙泊酚0.10-0.30μg/(kg.h)。右美托咪定组(简称D组)先用10 min静注右美托咪定,剂量为0.50μg/kg再用微量注射泵持续静脉泵入,剂量为0.30-0.60μg/(kg.h)。丙泊酚组(简称P组):先静注丙泊酚0.3-0.6 mg/kg,注药时间60 s,然后以微量注射泵持续泵入维持剂量为0.30-1.20 mg/(kg.h);3组均采用Ramsay分级标准,调整剂量使患者Ramsay评分控制在Ⅲ-Ⅳ级。分别记录起效时间,维持镇静的剂量,药物对呼吸、循环(RR、SPO2、HR、MAP)等的影响,苏醒拔管时间,不良反应发生情况及患者舒适度。结果:3组药物均能达到ICU病人所需的镇静效果。A组较P组循环波动少、丙泊酚用量少。患者谵妄、恶心呕吐等不良反应少,差异有统计学意义(P<0.05);A组较D组右美托咪定用量少,两组在心率、血压、呼吸等方面差异均无统计学意义(P>0.05)。拔管所需时间:P组与A组、D组相比,拔管所需时间差异有统计学意义(P<0.05)。结论:右美托咪定联合丙泊酚对ICU机械通气患者镇静效果满意,减少丙泊酚及右美托咪定的用量,血流动力学稳定,无呼吸抑制,不良反应低,经济适用。     

高频通气在肺抢救监护病房(PICU)中应用(附25例分析)

我们对PICU中25例危重患儿行高频通气(HFV)32例次(占同期机械通气病人的18.6％)。其中混合高频通气(CHFV)6例次,高频喷射通气(HFJV)10例次,高频正压通气(HFPPV)2例次,经鼻塞高频喷射给氧14例次。年龄范围:1天～10岁,主要原发病:重症肺炎伴呼衰、心衰,心肺复苏后,重症支气管哮喘,呼吸窘迫综合征等。经鼻气管内插管为高频通气主要途经。应用结果显示:经鼻塞高频给氧与普通给氧(口罩或头罩)相比,PaO_2和PaO_2/Fio2值明显上升(P<0.01),PaCO_2和PH无明显变化(P>0.05),混合高频通气组均无CO_2潴留,并提示其所需平均气道压(Paw)和吸气峰压值(PIP)较单纯常频通气时为低。本文对高频通气适应症、高频呼吸器参数的调节略加讨论。并指出:CO_2潴留和呼吸道湿化不足仍是高频喷射通气应用中存在的主要问题,为此可采取与常频通气交替使用,注意调节驱动力和频率等参数和加强气道管理等方法加以解决。